2015年5月28日 星期四

VSS 2015 Note

21.21 Long et al. developed a size stroop effect paradigm is which the real world size and the image size may have a different relation among test objects. They had observers to select one of the two objects with bigger sizes. The object with smaller image may have a bigger real world size. The RT for the congruent condition is smaller than the incongruent condition. For most objects, Size classification accuracy cannot predict identification performance, but stroop effect ER change. Basic level recognition is not necessary to activate real world size.

21.22 The authors explored the cortical representation in different areas in the ventral stream of the object categorical boundaries. They Focused on V1, V2, hV4 and LOC. The computed the correlation of voxel activations for different objects and used it as a measurement of distance. The within-category difference decreased while between-category distance increased from V1 to LOC. The less typical exemplar tend to have a greater distance from the centroid of the category.

22.24 They use fMRI adaptation paradigm. The stimuli were colored ring modulated in Red/green or luminance. The observers were adapted to blank, R/G or ACH ring and tested with R/G or ACH ring. Vo is identified by contrasting colored and ACH contrast. Without adaptation, V4,V3V and VO all shows a bias toward color rings. Adapted to R/G reduced R/G test activation everywhere, but ACH adaptor produced a significant reduction effect for R/G activation only in VO. The ACH adaptor produced more effect than R/G on ACH  test only in dorsal areas.
[I am not sure what is new about this study that we have not known already from previous literature. ]

22.26 Tyler demonstrated a new color induction effect in which one can perceive color of dot inducers on a blank field.

23.4072 The authors used a block design fMRI to measure BOLD response to images of six individuals in six expressions. They compute the correlation of voxel responses in FFA, OFA and STS. They then correlated the fMRI responses with extracted internal and external images. They found internal features correlated well with expression and external, identity.
[We can really use this paradigm for our ORE on facial expression experiment. We were able to extract various images features. Instead component analysis, we can just correlate these features with fMRI activation to observe which feature can predict BOLD activation to ORE.] 

26.4005 Using nominal or subjective equilluminance S-cone modulation colors has no effect on VEP.

26.4007 In V1, the BOLD activation for Glaucoma patients for ACH,RG or BY patterns are lower than normal. However, in LGN, glaucoma patients actually have greater activations.

26.4008 This paper from Kingdon's lab measured the fusion threshold for dichoptic colors. They showed that the fusion threshold increased with luminance contrast.

26.4080 The authors showed a novel Lemon illusion, in which the observers may perceive curvature on straight lines (thus, shape like a lemon) if the line is bound by curves.

26.4081  The authors suggested that Ebbinghaus illusion is not due to size contrast. The difference between target and background size is not sufficient (it is possible to have size contrast without illusion) nor necessary (one can produced the illusion by a squared contour surrounding the target).

33.3016 This study from Webster's lab measured the average color of a patch of random dots in which the color of a pixel was sample from a distribution along a color axis. They found that the variability of white setting increased significantly with any added random variability in the image.    

33.3018 The authors showed that the afterimage for induced color is not complementary colors but biased toward S-cone contribution.

33.3049 The authors changed the viewpoint and expression of facial images and measured the classification of BOLD activations for those images.  They found that IT can classify both viewpoint and expression. However, when there is  a joined change in viewpoint and expression. The expression difference dominate classification.

33.4037 Boynton used M-sequence to measure fMRI pRF. They found that pRF ignored the scotoma in stimulus presentation, suggesting a filling-in process is involved. 

33.4041  Mulligan used a titration method to calibrate a display without photometer. The stimulus including stripes of a checkerboard of two end points to be bisected and a gray. It alternating with gray-upper-end and gray-lower-end checkerboards. If the gray is too bright, it would move to an opposite direction form when it is too dark. Thus, we can use minimum motion as a criterion to determine the gray level that bisect the range.

33.4087 The authors found that the fMRI activation in PPA and surrounding areas can classify building of different styles, but not different architects of the same style.

36.3001 The authors made a review on several aspects of brain responses to symmetry patterns.

36.4001 McCourt et al. manipulated the luminance of the collinear or the context bars in the White illusion display. They found that the illusion mainly changed with the collinear luminance and much less with context luminance.

35.24 This study from Gallent's lab decomposed images into features (SF, depth, surface orientation). Send the observers to fMRI scanner and estimated the weighting of each feature per voxel. Low level features are from converting input images Gabor wavelets. The depth were from depth map (the test images are rendered from a 3D model) and the orientation is from surface norms. [CC: this is clever. Using the rendered images, they completely avoid the tedious task of image understanding). The local features predicts V1 responses. But the orientation and depth combined predicts PPA responses. They can then construct the voxel receptive field, with particular depth and surface orientation selectivity.    

35.28 The authors compared human behavior data with electrophysiological response to nature scene. The behavior task is simple 2AFC detection task. The target was Gabor patch on a patch of a natural scene background. The result is a typical no-dipper TvC function (for background was a patch of nature scene and thus provided little excitation to the detector). They then measured the voltage sensitive dye imaging on monkey brain to the target. The brain area for the target is used as ROI. They then measured the response to background in target ROI in each trial and got a histogram of response distribution. They then computed neurometrics function for various background and estimated threshold for the target contrast that gave d'=1 for different background contrasts. The response, when appropriately scheduled, fit human performance data well.

52.13 The authors use emotional faces and perceptual similarity task (whether two faces had the same emotion). They showed that there is culture difference between Chinese and British in perceptual similarity task. There is a difference in categorization. They then repeated the experiment with lower and higher half faces. Again, there is no difference between culture. The categorization showed a difference in the lower face region, not in the upper face regions.    They then tried two databases (Chinese and Caucasian). Again, a own-group advantage in lower face regions.

52.15 The authors found that there is a low correlation between different holistic face tasks (inversion, composite and part-whole). Only face inversions correlated with face perception (0.39). There is no correlation between composite face task and face perception,


53.4002 The authors used typical phase tagging paradigm but swap 2D spatial change with depth change. In this case, they claimed to be able to map depth tuning in cortex. [Their result seems to be a very preliminary stage. It remains to be seen whether their method holds].

53.4007 The authors measured the fMRI bold response to rings of different orientation. They used MVPC to identify the voxels that contribute most to classification and use population receptive field to identify the pRF of these voxels. They found that the ones that contributed most to classification are those tune to the edges of the rings.

61.13 The authors uses MEG to measure broadband field response, that is normally acquired with Ecog. The signal is a broadband increase related to baseline, other than the stimulus driven response. It is a proxy for mean local spiking activity and is correlated with fMRI BOLD activation. The MEG field potential is weaker and more pronounced at high frequency. It is spatially localized by low in SNR. They used a denoising algorithm. The noise is acquired from PCA of channels that do not respond to the stimuli (e.g., frontal electrodes in visual stimulation).   In that way, the claim to be able to measure reliable field potential.

61.14 Following the previous presentation from the same lab, they compared MEG measured local field potential and BOLD. They extract several frequency band from MEG signal and correlated it with BOLD and found individual bands do not correlate with BOLD well, but broadband field potential.

61.15 They modeled ganglion cell with normalized response then predict the ganglion responses to nature images and compute the statistics of the natural images and retinal signals. The retinal off-neurons dominated low frequency response and there is an interaction in contrast gain control between P- and M-cells.  


63.4066 This paper from Daniel Baker's lab is also identical to YiChen's thesis. We need to get it published ASAP.